A technique to maintain the quality of grain without pesticide use is a Cooling. It involves heat and moisture transfer processes. To observe the changes during that process, a theoretical simulation model is developed and some experiments have been conducted. The model is comprised on partial differential equations and some empirical equations. The partial differential equations are solved by finite difference numerical method. The empirical equations are selected from different studies using their correlations, in the lower range of temperatures. The theoretical simulation model has been used to predict the changes in heat and moisture transfer in deep bed grain cooling. The model has been verified against previous research. The predicted results are in good agreement with the previous research data. Also the field data from Berwick experiments (UK) for the years 1993-1995 have been simulated and found in reasonable agreement with field results except for greater rewetting in the air entry region in the simulation results.